Insecticide and method of making



Patented July 13, 1937 INSECTICIDE PATENT OFFIE AND METHOD OF MAKINGCharles B. Gnadinger, Minneapolis, Minn.

No Drawing. Application June 19, 1933,

Serial No. 676,534

. 9 Claims.

This invention relates generally to the production of insecticidalsubstances, and particularly to a pyrethrum-soap insecticide, and methodof producing the same.

To understand the problems concerned in the production of an idealpyrethrum-soap insecticide, a discussion of the general subject isdesirable. Oleo-resin' of. pyrethrum emulsified with liquid soap hasbeen used as an insecticide. Extracts or pyrethrum in alcohol, acetoneor petroleum oils, emulsified with soaps, have also been used. However,all of those substances are objectionable for one reason or another.

It is known that aqueous solutions of soap are hydrolized, becomingalkaline and thus destroy' ing, by saponification, the activity of thepyrethrins which are esters. The more dilute the soap solutions, withincertain limits, the greater the hydrolysis of the soap. In the ordinarydilute solution, therefore, the pyrethrins are quickly decomposed. Thepresence of alcohol also facilitates decomposition. It will be seen fromthe foregoing that the problem of producing an ideal pyrethrum-soapinsecticide, is difiicult.

The ideal pyrethrum-soap insecticide should.

contain a high concentration of pyrethrum, on which the toxicityprincipally depends; should contain the greatest possible amount ofsoap, so that suificient Wetting and spreading is obtained, when theproduct is used at high dilutions; should contain the minimum amount ofwater, to prevent hydrolysis of the soap, and resultant saponificationof the pyrethrins, with corresponding destruction, or great reduction ofinsect toxicity; should be a homogeneous liquid, readily miscible withcold water; and the pyrethrum should be dissolved in an oil, preferablyone having marked ovicidal and insecticidal properties.

I have extensively experimented with a large number of solvents andemulsifiers, in order to meet the above specifications for idealsoappyrethrum' insecticides, and have finally succeeded in producingsuch substances.

Among other things, I have discovered that certain essential oils, such,for example, as steam distilled pine oil, and destructively distilledpine oil, are good solvents for the oleo-resin of pyrethrum. Also cedaroil, pine tar oil, various pine tar distillates are usable.

It is known that certain organic solvents such as ethylene dichloride,petroleum oils, and turpentine, dissolve the pyrethrins. I have found,however, that the amount of soap which can be incorporated with thesedifferent solvents varies greatly. Moreover, the type of productobtained when these solvents (or extracts of pyrethrum made with them)are mixed with soaps or other emulsifier varies markedly. For example,neither petroleum oils nor turpentine form homogeneous mixtures withpotassium oleate, but the oils are 5 emulsified, forming opaque mixtureswhich gradually separate on prolonged standing. The ideal insecticideshould be, among other things, homogeneous.

Moreover, there are certain oily liquids which, 10 when mixed with soap,become readily soluble in water. The best example is cresol which isalmost insoluble in water but which becomes easily soluble when mixedwith soap, as in the Liquor Cresolis Compositus of the United States 1Pharmacopoeia. Coal tar creosote oil with soaps forms milky emulsionswhen the degree of dilution is great. Soap emulsions of these oils arewidely used as disinfectants.

I have found that pine oil, steam distilled pine 20 oil and otheressential oils iorm homogeneous mixtures with potassium oleate, andthese mixtures are clear and have the appearance of true solutions anddo not separate on standing, I have found that the amount of soap whichcan 5 be incorporated is greatest for pine oil. The amount of soap whichcan be incorporated also depends upon the type of soap. Rosin soap isthe least soluble of the soaps that I have investigated; potassiumoleate is intermediate in 30 solubility, while potassium-castor oil soapis the mostsoluble.

For.the production of an excellent insecticide embodying all theproperties above mentioned, the procedure is as follows: Extract with aVolatile solvent, preferably using ethylene dichloride, 3000 pounds ofpyrethrum flowers containing 0.90 per cent pyrethrins; other solventssuch as naptha, petroleum ether and benzine can be used, or any volatilesolvent which will prop- 40 erly extract the active principles of theflowers, that is the pyrethrins. The volatile solvent is then distilledoff, in vacuum, to obtain an oleoresin of pyrethrum. The weight of theoleoresin obtained depends on the solvent used. With ethylene dichloridewhen using the amount mentioned, I obtain about 200 pounds ofoleo-resin, and with petroleum ether about 110 pounds. The

oleo-resin which contains substantially all the pyrethrins from the 3000pounds of flowers (to-- 5 gether with more or less inert matter,depending on the solvent used) is now dissolved in sulficient steamdistilled pine oil or equivalent essential oil to make a total volume of75 gallons.

About gallons of pine oil are required. 55

If the pyrethrum flowers contain more than 0.90 per cent pyrethrins, thetotal volume of the pine oil solution is made proportionately greater.If the flowers contain less than 0.90 per cent pyrethrins the volume ofthe pine oil solution is made proportionately less. The pine oilsolution is thus standardized to contain in each gallon, the activeprinciples of 40 pounds of pyretl'irum flowers having a pyrethrincontent of 0.90 per cent.

I next prepare a mixture of soap in pine oil as follows: Steam distilledpine oil or equivalent essential oil about 66 gallons; castor oil orequivalent vegetable oil, about 1038 pounds; potassium hydroxide or anhydroxide of an alkali metal, about 222 pounds (just sufiicient tosaponify the castor oil or equivalent oil as determined by titration)water, about 27 gallons. This soap is prepared with a minimum amount ofheat, and

after cooling to room temperture, about 75 galions of the pine oiloleo-resin solution is added while mixing, to make a total volume ofabout 300 gallons.

Heat should not be employed, after the pyrethrum extract has been mixedwith the soap. The use of excess alkali in making the soap should beavoided. For certain uses, potassum soaps should be used in preferenceto sodium soaps, since potassium is a plant food and sodium is not.

The emulsion obtained by the above procedure is clear, homogeneous, doesnot separate on standing, and has all the appearance of a true solution,and dissolves readily in cold water.

Pine oil and similar oils have considerable toxicity and repellentaction to insects. Pine oil can be emulsified with soap containing avery low percentage of water, and is solvent for the pyrethrins.

The substance produced herein is a concentrated solution of pyrethrum inan essential oil such as pine oil which is emulsified with castor oil(or other vegetable oil) soap. The pyrethrins are first dissolved inpine oil or equivalent essential oil to prevent saponiflcation. Theproduct contains only 12 per cent of water which is not sufiicient tocause hydrolysis of the 44 per cent of soap, and thus saponification ofthe pyrethrins by hydrolized soap is avoided.

. I have used steam distilled pine oil, but oils such as destructivelydistilled pine oil, cedar oil, pine tar oil, various pine tardistillates and coal tar creosote oil can be used. If desired, derrisextract, or rotenone can be added to the pine oilpyrethrum extract.

Potassium-castor oil soap has been used as an emulsifier, but othersubstances such as rosin soap or soaps made from corn oil fatty acids,cocoanut o'il fatty acids and the like can be used. Triethanolamineoleate can also be used instead of potassium or sodium oleate.

. The above insecticide can be diluted with water for spraying plants,and the substances in this dilute solution remain in homogeneoussuspension from which neither the pyrethrins, nor the pine oil, nor thesoap separates. For aphids one part of the insecticide is diluted with400 parts of water.

No spreader is added since the soap and pine oil serve the purpose. Thepine oil also increases the toxicity. For leaf rollers and moreresistant insectsa dilution of one part of the insecticide to parts ofwater may be used, and

such a solution -will not injure tender greenhouse plants. Thisinsecticide is efiective against aphids, leaf rollers and many otherinsects, and is also toxic to the eggs of insects.

My product is a liquid readily miscible with water which does notseparate on standing, saponification of the pyrethrum is prevented, noadditional spreader is required and it is more toxic to insects thanordinary soap pyrethrum mixtures having the same soap and pyrethrumcontent.

It is seen that the oil used in preparing my product should be one whichcan be emulsified with soap containing a very low percentage of water,which 'will take up a very large proportion of soap, and must be asolvent for pyrethrins. It is also desirable that the oil be toxic orrepellent to insects. A standardized concentrated solution ofpyrenthrins in this oil is prepared by dissolving oleo-resin ofpyrethrum in it. A soap is then prepared in the oil-pyrethrum solution,of such concentration that the product can be greatly diluted with waterwithout separation of the oil, pyrethrins, or soap, and still beextremely toxic to insects. The emulsion is stable.

It will be noted that I use a readily volatile sol ent such as ethylenedichloride, naphtha, petroleum ether, or benzine for extracting theactive principles of the pyrethrum flowers, so that the solvent may bedistilled ofi without the use of excessive heat and thus obtain anoleoresin of pyrethrum as the extract. In the appended claims, the termextract of pyrethrum" is used to denote an extract of this type, thatis, and extract without any substantial amount of the solvent present.

I claim as my invention:

1. The process of making an insecticide which consists in dissolvingoleo-resin of pyrethrum in an oil of the group consisting of pine oil,cedar oil, pine tar oil and pine tar distillates, making a soapsubstantially free from alkali and contain- 2. The process of making aninsecticide which 4 consists in dissolving oleo-resin of pyrethrum inpine oil, makinglan alkali free. soap containing pine oil, and then'mixing the pine oil oleo-resin of pyrethrum solution with the pine oilsoap solution to form a concentrated insecticide.

3. The process, of making an insecticide which consists in dissolvingoleo-resin of pyrethrum in pine oil, making an alkali free vegetable oilsoap containing pine oil, and then mixing the pine oil oleo-resin ofpyrethrum solution with the pine oil soap to form a concentratedinsecticide.

4. The process of making an insecticide which consists in dissolvingoleo-resin of pyrethrum in pine oil, making a substantially alkali free.castor oil soap containing pine oil, and then mixing the pine oiloleo-resin of pyrethrum solution with the castor oil soap containingpine oil to form a concentrated insecticide.

5. A stable and readily water soluble insecticide consisting of a pineoil solution of oleo-resin of pyrethrum :l a substantially alkali freevegetable oil soap.

. 6. A stable and readily water soluble insecticide consisting ofa pineoil solution of oleo-resin of pyrethrum and a substantially alkali freecastor oil soap.

'7. A stable and readily water soluble insecticide consisting of pineoil, oleo-resin of pyrethcastor oil soap.

8. A stable and readily water soluble insectitrated insecticideconsisting of pine oil, oleocide consisting of a solution of oleo-resinof pyresin of pyrethrum, and a substantially alkali rethrum in anessential oil of the group consistfree potassium castor oil soap, saidsoap constiing of pine oil, cedar oil, pine tar oil and pine tuting atleast substantially 44 per cent of the 5 tar. distillates and asubstantially alkali free product.

vegetable oil soap. CHARLES B. GNADINGER.

9. A stable and readily water soluble concen-

